.--..
..
,.-
j 1 /
Brief
Description
of
,System
The
Radio
Shack TRS-80 Model II
is
a disk-based computer system
consisting
of
two major components:
• a Display Console with built-in disk drive
• a separate Keyboard Enclosure
The
Operating System software
is
loaded from diskette by a built-in
"bootstrap"
program.
Here
is
a briefdescription
of
the functional elements
of
the Computer.
Processor
At
the
heart
of
the
Computer
is
a Z-80A microprocessor operating at its
maximum design speed (4 million machine-cycles per second).
The
processor receives power-up and reset instructions from read-only
memory
(ROM).
After the TRSDOS initialization program
is
loaded from
disk, this
ROM
is electronicallyswitchedout
of
the system and replaced with
random
access memory (RAM).
Random Access Memory (RAM)
The
basicsystem includes 32K bytes
of
randomaccess memory.
(lK
= 1024.)
An
additional32Kbytes can be added, for a total
of
64K bytes
of
addressable
RAM.
Video Display
The
Video
Display has its own LSI controller chip, to free the Z-80A
processor from display refresh and related tasks.
The
Displayoffers two modes:
80
characters by24 lines, and40 charactersby
24 lines.
The
displayable character set includes the full ASCII set (upper and
lower case alphabet, numbers, and special symbols), plus
32
graphics
characters.
Each
character can be displayed as white on black
or
black
on
white. See Displayable Characters in Section
7.
5
To Next Page
Loading...
Need help?
General
